Implement SystemSet
for BoxedSystemSet
#8839
Closed
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Objective
Solution
Explicitly implement
SystemSet
(implyingIntoSystemSet
) forBoxedSystemSet
Rationale
BoxedSystemSet
doesn't "need" to implementSystemSet
because you can call the methods on the trait object reference. However, that means it can't beIntoSystemSet
, since it can't unwrap the internal type, and you can't call.into_system_set(self)
ondyn SystemSet
, because it isn't sized.The trivial solution is to
impl SystemSet for Box<dyn SystemSet>
. But that introduces a problem becauseIntoSystemSetConfig
is implemented separately forSystemSet
andBoxedSystemSet
, and forSystemSet
it boxes it before passing to the constructor. So to avoid this double-boxing I just added a defaultinto_boxed()
method that turns a normal, non-trait-object system set into aBoxedSystemSet
, and override it forBoxedSystemSet
to just return itself.